Re: streamline plot with stUseScalarArray = True

Hi Radovan,

Sorry for the late response. We had a burst of consulting activity
yesterday. I guess everybody came back from vacation and had
immediate software questions. :-)

Anyway, you can't color streamlines according to another field like
you can with vectors. So, how about instead using curly vectors, and
then coloring according to a third field that way? The functions to
use are Ngl.vector_scalar, or Ngl.vector_scalar_map if you want to do
this over a map.

We have some examples of this. Go to:

   http://www.pyngl.ucar.edu/Examples/gallery.shtml

and look at examples ngl03p and ngl06p, and vector_pop. These examples
don't have curly vectors, but this can easily be remedied by setting
the "vcGlyphStyle" resource to "CurlyVector". (See vector_pop.py on
the same page for an example of curly vectors.)

Let me know if this is not the solution you were hoping for.

--Mary

On Tue, 4 Sep 2007, radovan bast wrote:

> dear all,
>
> first, please let me thank the pyngl/ncl developers for their great work!
>
> i would like to plot a streamline plot where the coloring
> uses a scalar data array.
> for instance i manage to plot the streamline plot with:
>
> plot = Ngl.streamline(wks, u_array, v_array, resources)
>
> and now i would like to color the streamlines according to one vector
> component (i.e. the v_array) or another 2d array
>
> i understand that i must specify:
>
> resources.stMonoLineColor = False
> resources.stUseScalarArray = True
>
> but how can i specify how/which scalar data array has to be used for the
> coloring?
>
> since i don't i get:
>
> warning:StreamlinePlotInitialize: No scalar data: using streamline magnitude
> for levelsa
> and pyngl colors according to the norm of the vector
>
> the manual indicates: the resource stScalarFieldData is [to be] set with a
> valid ScalarField object
> i don't know how this can be done in practice and i would be very grateful
> for every hint.
>
> best greetings,
>
>
> radovan
> _______________________________________________
> pyngl-talk mailing list
> pyngl-talk_at_ucar.edu
> http://mailman.ucar.edu/mailman/listinfo/pyngl-talk
>
_______________________________________________
pyngl-talk mailing list
pyngl-talk_at_ucar.edu
http://mailman.ucar.edu/mailman/listinfo/pyngl-talk
Received on Wed Sep 05 2007 - 09:04:28 MDT